There have been known moving body systems using linear motors. Among such moving body systems are those using secondary-side-on-ground type linear motors. The secondary-side-on-ground type is a type in which linear motors are mounted on a mover (moving body) and magnets are disposed on a stator (rail). As a moving body system of this type, for example, there is known a moving body system in which magnets with south poles and magnets with north poles are alternately disposed on a rail (movement path) and a moving body having linear motors mounted thereon moves along the rail, as disclosed in Patent Literature 1. The moving body includes a position detector that detects the poles of magnets. The continuous positions of the moving body are determined based on detection results obtained by the position detector.